复合主键和外键Code First

Question

我正在尝试创建2个实体，即用户评论和用户评论，其中用户评论具有一个组合主键，该主键是用户的ID，一个被评论并进行过操作的用户，此组合主键也是用户表中的主键，但是EF正在创建一个我看不到该点的额外列，同样，当我将用户评论对象保存到数据库时，该列也不会被填充，因此始终为空。

这导致当我尝试检索带有评论的用户时，除非User_SubjectId列包含该用户的ID，否则评论集合始终为空。

我的查询是这样的

 return _context.Users
                .Include(u => u.Reviews)
                .Where(u => u.SubjectId.Equals(subjectId));

评论集合始终为空

用户评论实体

using System;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

namespace API.Data.Entities
{
    public class UserReview
    {
        [Key, Column(Order = 0), ForeignKey("Reviewer")]
        public string ReviewerId { get; set; } //The user that wrote the review

        [Key, Column(Order = 1), ForeignKey("ReviewedUser")]
        public string ReviewedUserId { get; set; } //The user who was reviewed

        [Required]
        [Range(1, 5)]
        public int Rating { get; set; }

        [Required]
        public DateTimeOffset DateCreated { get; set; }

        [Required]
        public virtual User Reviewer { get; set; }

        [Required]
        public virtual User ReviewedUser { get; set; }
    }
}

用户实体是这样的

public class User
    {
        [Key]
        [Required]
        public string SubjectId { get; set; }

        public User()
        {                
            Reviews = new List<UserReview>();
        }

        public virtual ICollection<UserReview> Reviews { get; set; }    
    }

但是，当我添加迁移时，如该图所示，在UserReviews表中又创建了另一列，该列为User_SubjectId

我不知道这是EF中的错误还是我的映射错误，无论如何有什么想法？

谢谢

Answer 1

您必须使用ReverseProperty批注。

public class UserReview
{
    [Key, Column(Order = 0), ForeignKey("Reviewer")]
    public string ReviewerId { get; set; } //The user that wrote the review

    [Key, Column(Order = 1), ForeignKey("ReviewedUser")]
    public string ReviewedUserId { get; set; } //The user who was reviewed

    [Required]
    [Range(1, 5)]
    public int Rating { get; set; }

    [Required]
    public DateTimeOffset DateCreated { get; set; }

    [Required]
    public virtual User Reviewer { get; set; }

    [Required)]
    public virtual User ReviewedUser { get; set; }
}

public class User
{
    [Key]
    [Required]
    public string SubjectId { get; set; }

    public User()
    {                
        Reviews = new List<UserReview>();
    }

    [InverseProperty("ReviewedUser")] // or Reviewer.
    public virtual ICollection<UserReview> Reviews { get; set; }    
}

在我看来，这是使用流利的映射时更易于配置的事情。